Lawyer in the article suggests game mechanics are copyrightable, but that is definitely not the case. Game mechanics aren't protected by anything (and shouldn't be). Art and music you can make the case for.
I fear the US case law does not agree with this statement. (And we are talking about US in this specific case.)
It would be quite easy to describe game mechanics as the game counterpart to novels' plot. Now, the US have a tradition of considering certain aspects of the plots are copyrightable [1], for example certain non-stock abilities of characters like "having the ability to grow when receiving a powerup, shrinking when touched by enemies, being able to kill enemies by jumping over them but being killed by them if touched by them". Obviously this is a very grey area, but one doesn't get to easily dismiss the problem because "they shouldn't be".
